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Abstract:

Methods, systems and devices for evaluating the integrity of a uterine
cavity. A method comprises introducing transcervically a probe into a
patient's uterine cavity, providing a flow of a fluid (e.g., CO2)
through the probe into the uterine cavity and monitoring the rate of the
flow to characterize the uterine cavity as perforated or non-perforated
based on a change in the flow rate.

Claims:

1.-11. (canceled)

12. A system for treating a patient's uterus, said system comprising: a
probe having a working end adapted to be positioned in a patient's
uterine cavity; means for introducing a first fluid into the working end;
means for introducing a second fluid into the uterine cavity exterior of
the working end; means for performing first and second monitoring tests
of parameters of the first and second fluids to thereby characterize a
uterine wall; and means for actuating an ablation mechanism in the
working end upon characterization of the uterine wall as intact.

13. The system of claim 12 wherein the actuating means is automatically
actuated by a controller.

14. A system of characterizing a patient's uterus, comprising: a probe
having working end adapted to be positioned in a patient's uterine
cavity; means for flowing a first fluid into the working end; means for
flowing a second fluid into the uterine cavity exterior of the working
end; means for recording a first pressure in the first fluid when during
the second fluid flow; means for recording a second pressure in the first
fluid after termination of the second fluid flow; means for comparing the
first and second pressures to thereby characterize the uterine wall as
perforated or non-perforated.

15. The system of claim 14 further comprising means for actuating an
ablation mechanism carried by the working end.

16. The system of claim 15 wherein the means for actuating is
automatically actuated by a controller.

17.-25. (canceled)

26. A system for characterizing a patient's uterus, said system
comprising: an expandable structure positionable in a patient's uterine
cavity, the structure comprising an expandable thin wall sheath; means
for inflowing a gas into the uterine cavity exterior of expandable
structure; means for monitoring the gas inflow with flowmeter; and means
for determining whether the inflow exceeds a first flow rate and then
decays and remains below a second flow rate for an interval of at least 1
second.

27. The system of claim 26 wherein the determining means detects an
interval of at least 2 seconds, 5 seconds, or 10 seconds.

28. The system of claim 26 wherein the first flow rate is at least 0.010
SLPM.

29.-31. (canceled)

32. The system of claim 26 wherein expandable structure comprises a frame
in an interior chamber of an expandable thin wall sheath, further
including the step of applying a negative pressure to the interior
chamber to suction they sheath against the frame.

[0003] The present invention relates to electrosurgical methods and
devices for global endometrial ablation in a treatment of menorrhagia.
More particularly, the present invention relates to applying
radiofrequency current to endometrial tissue by means of capacitively
coupling the current through an expandable, thin-wall dielectric member
enclosing an ionized gas.

[0004] A variety of devices have been developed or proposed for
endometrial ablation. Of relevance to the present invention, a variety of
radiofrequency ablation devices have been proposed including solid
electrodes, balloon electrodes, metalized fabric electrodes, and the
like. While often effective, many of the prior electrode designs have
suffered from one or more deficiencies, such as relatively slow treatment
times, incomplete treatments, non-uniform ablation depths, and risk of
injury to adjacent organs.

[0005] For these reasons, it would be desirable to provide systems and
methods that allow for endometrial ablation using radiofrequency current
which is rapid, provides for controlled ablation depth and which reduce
the risk of injury to adjacent organs. At least some of these objectives
will be met by the invention described herein.

[0006] 2. Description of the Background Art

[0007] U.S. Pat. Nos. 5,769,880; 6,296,639; 6,663,626; and 6,813,520
describe intrauterine ablation devices formed from a permeable mesh
defining electrodes for the application of radiofrequency energy to
ablate uterine tissue. U.S. Pat. No. 4,979,948 describes a balloon filled
with an electrolyte solution for applying radiofrequency current to a
mucosal layer via capacitive coupling. US 2008/097425, having common
inventorship with the present application, describes delivering a
pressurized flow of a liquid medium which carries a radiofrequency
current to tissue, where the liquid is ignited into a plasma as it passes
through flow orifices. U.S. Pat. No. 5,891,134 describes a radiofrequency
heater within an enclosed balloon. U.S. Pat. No. 6,041,260 describes
radiofrequency electrodes distributed over the exterior surface of a
balloon which is inflated in a body cavity to be treated. U.S. Pat. No.
7,371,231 and US 2009/054892 describe a conductive balloon having an
exterior surface which acts as an electrode for performing endometrial
ablation. U.S. Pat. No. 5,191,883 describes bipolar heating of a medium
within a balloon for thermal ablation. U.S. Pat. No. 6,736,811 and U.S.
Pat. No. 5,925,038 show an inflatable conductive electrode.

BRIEF SUMMARY

[0008] The following presents a simplified summary of some embodiments of
the invention in order to provide a basic understanding of the invention.
This summary is not an extensive overview of the invention. It is not
intended to identify key/critical elements of the invention or to
delineate the scope of the invention. Its sole purpose is to present some
embodiments of the invention in a simplified form as a prelude to the
more detailed description that is presented later.

[0009] The present invention provides methods, systems and devices for
evaluating the integrity of a uterine cavity. The uterine cavity may be
perforated or otherwise damaged by the transcervical introduction of
probes and instruments into the uterine cavity. If the uterine wall is
perforated, it would be preferable to defer any ablation treatment until
the uterine wall is healed.

[0010] A method of the invention comprises introducing transcervically a
probe into a patient's uterine cavity, providing a flow of a fluid (e.g.,
CO2) through the probe into the uterine cavity and monitoring the
rate of the flow to characterize the uterine cavity as perforated or
non-perforated based on a change in the flow rate. If the flow rate into
the cavity drops to zero or close to zero within a predetermined time
period, this indicates that the uterine cavity is intact and not
perforated. If the flow rate does not drop to zero or close to zero, this
indicates that a fluid flow is leaking through a perforation in the
uterine cavity into the uterine cavity or escaping around an occlusion
balloon that occludes the cervical canal.

[0011] Embodiments herein provide a method of characterizing a patient's
uterus, comprising introducing a flow of a fluid into a uterine cavity of
a patient; and monitoring the flow to characterize the uterine cavity as
at least one of perforated or non-perforated based on a change in a rate
of the flow. Introducing may be, for example, transcervically introducing
a probe into the uterine cavity, and introducing the flow through the
probe.

[0012] Monitoring may include providing a signal, responsive to the rate
of flow, that characterizes the uterine cavity as at least one of
perforated or non-perforated. As an example, monitoring may include
generating a signal responsive to the rate of flow not dropping below a
predetermined level, the signal characterizing the uterine cavity as
perforated. In embodiments, the predetermined level is 0.05 slpm.

[0013] In embodiments, monitoring comprises generating a signal responsive
to the rate of flow dropping below a predetermined level, the signal
characterizing the uterine cavity as non-perforated. The predetermined
level may be, for example, 0.05 slpm.

[0014] In further embodiments, monitoring comprises monitoring a rate of
flow after a predetermined first interval after initiation of the flow.
The first interval may be, as examples, at least 5 seconds, at least 15
seconds, or at least 30 seconds.

[0015] Monitoring may additionally include monitoring a rate of flow over
a second predetermined interval after the first interval. The second
interval may be a least 1 second, at least 5 seconds, or at least 10
seconds, as examples.

[0016] In additional embodiments, monitoring includes providing a signal,
responsive to the rate of flow, that characterizes the uterine cavity as
at least one of perforated or non-perforated, and wherein the signal is
at least one of visual, aural and tactile.

[0017] In embodiments, prior to introducing the flow, a member is
positioned within the cervical canal that substantially prevents a flow
of the fluid out of the uterine cavity. Introducing may include
transcervically introducing a probe into the uterine cavity, and
introducing the flow through the probe, with the member positioned about
an exterior of the probe. The member may be expanded in the cervical
canal.

[0018] In embodiments, the fluid is a gas or a liquid.

[0019] In additional embodiments, introducing includes transcervically
introducing a probe into the uterine cavity, and introducing the flow
through the probe. The probe has a working end with an energy-delivery
surface for ablating uterine cavity tissue. Responsive to the uterine
cavity being characterized as perforated, energy delivery surface is
disabled. Alternatively or additionally, responsive to the uterine cavity
being characterized as non perforated, activation of the energy delivery
surface may be enabled or even caused to happen automatically.

[0020] In embodiments, a method of endometrial ablation is provided, the
method including introducing an ablation probe into a uterine cavity of a
patient; flowing a fluid from a fluid source through the probe into the
uterine cavity; monitoring the rate of the flow of the fluid into the
uterine cavity to characterize the cavity as at least one of perforated
or non-perforated based on a change in the flow rate; and responsive the
to the uterine cavity being characterized as non perforated, activating
the ablation probe to ablate an interior of the uterine cavity.

[0021] For a fuller understanding of the nature and advantages of the
present invention, reference should be made to the ensuing detailed
description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to better understand the invention and to see how it may
be carried out in practice, some preferred embodiments are next
described, by way of non-limiting examples only, with reference to the
accompanying drawings, in which like reference characters denote
corresponding features consistently throughout similar embodiments in the
attached drawings.

[0023]FIG. 1 is a perspective view of an ablation system corresponding to
the invention, including a hand-held electrosurgical device for
endometrial ablation, RF power source, gas source and controller.

[0024]FIG. 2 is a view of the hand-held electrosurgical device of FIG. 1
with a deployed, expanded thin-wall dielectric structure.

[0025]FIG. 3 is a block diagram of components of one electrosurgical
system corresponding to the invention.

[0026] FIG. 4 is a block diagram of the gas flow components of the
electrosurgical system of FIG. 1.

[0027] FIG. 5 is an enlarged perspective view of the expanded thin-wall
dielectric structure, showing an expandable-collapsible frame with the
thin dielectric wall in phantom view.

[0028] FIG. 6 is a partial sectional view of the expanded thin-wall
dielectric structure of FIG. 5 showing (i) translatable members of the
expandable-collapsible frame a that move the structure between collapsed
and (ii) gas inflow and outflow lumens.

[0029] FIG. 7 is a sectional view of an introducer sleeve showing various
lumens of the introducer sleeve taken along line 7-7 of FIG. 6.

[0030]FIG. 8A is an enlarged schematic view of an aspect of a method of
the invention illustrating the step introducing an introducer sleeve into
a patient's uterus.

[0031]FIG. 8B is a schematic view of a subsequent step of retracting the
introducer sleeve to expose a collapsed thin-wall dielectric structure
and internal frame in the uterine cavity.

[0032] FIG. 8C is a schematic view of subsequent steps of the method,
including, (i) actuating the internal frame to move the a collapsed
thin-wall dielectric structure to an expanded configuration, (ii)
inflating a cervical-sealing balloon carried on the introducer sleeve,
and (iii) actuating gas flows and applying RF energy to contemporaneously
ionize the gas in the interior chamber and cause capacitive coupling of
current through the thin-wall dielectric structure to cause ohmic heating
in the engaged tissue indicated by current flow paths.

[0033] FIG. 8D is a schematic view of a subsequent steps of the method,
including: (i) advancing the introducer sleeve over the thin-wall
dielectric structure to collapse it into an interior bore shown in
phantom view, and (ii) withdrawing the introducer sleeve and dielectric
structure from the uterine cavity.

[0034] FIG. 9 is a cut-away perspective view of an alternative expanded
thin-wall dielectric structure similar to that of FIGS. 5 and 6 show an
alternative electrode configuration.

[0035]FIG. 10 is an enlarged cut-away view of a portion of the expanded
thin-wall dielectric structure of FIG. 9 showing the electrode
configuration.

[0036]FIG. 11 is a schematic view of a patient uterus depicting a method
corresponding to the invention including providing a flow of a fluid
media into the uterine cavity and monitoring the flow rate to
characterize the patient's uterine cavity as intact and non-perforated.

[0037] FIG. 12 is a perspective view of the ablation device of FIGS. 1-2
with a subsystem for checking the integrity of a uterine cavity.

[0038]FIG. 13 represents a block diagram of a subsystem of the invention
for providing and monitoring a fluid flow into the patient's uterine
cavity.

[0039] FIG. 14 represents a diagram indicating the steps of an algorithm
for providing and monitoring a fluid flow into the patient's uterine
cavity.

[0040] FIG. 15 is a chart illustrating gas flow rates into the uterine
cavity over time that will result in three conditions to thereby
characterize the uterine cavity as non-perorated or perforated.

[0041]FIG. 16 represents a diagram indicating the steps of an algorithm
for providing and monitoring a fluid flow related to the test method of
FIG. 15.

[0042] FIG. 17 is a schematic view of another system and method for
providing and monitoring a fluid flow to characterize the integrity of a
uterine cavity.

[0043] FIG. 18A is a schematic view of system with an expandable working
end properly deployed in the uterine cavity, and illustrates a variation
of a method for characterizing the integrity of a uterine cavity, wherein
a first stage of a two-stage test which monitors CO2 flows into the
uterine cavity exterior of the working end or dielectric structure.

[0044] FIG. 18B illustrates the second stage of the two-stage test which
monitors CO2 flows in the uterine cavity exterior of the dielectric
structure in response to Argon gas flows into the interior chamber of the
dielectric structure.

[0045] FIG. 19 is a box diagram illustrating the steps of a second stage
test as illustrated in FIG. 18B.

[0046] FIG. 20A is a schematic view of an expandable working end that is
not deployed in the uterine cavity and positioned in a uterine wall
perforation, and illustrates a first stage of a two-stage test which
monitors CO2 flows into the uterine cavity exterior of the working
end.

[0047] FIG. 20B illustrates the second stage of the two-stage test which
monitors CO2 flows in the uterine cavity exterior of the dielectric
structure in response to Argon gas flows into the interior chamber of the
dielectric structure.

[0048]FIG. 21 is a box diagram illustrating the steps of a variation of
the second stage of a two stage test.

[0049] FIG. 22A is a schematic view of an expandable dielectric deployed
in the uterine cavity and illustrates a test in which the dielectric is
suctioned against an interior frame by a negative pressure source.

[0050] FIG. 22B is a schematic view of the expandable dielectric of FIG.
22A improperly deployed in a perforated wall of a uterine cavity and
illustrates the test wherein the dielectric is suctioned against the
interior frame by the negative pressure source.

[0051]FIG. 23 is an expanded schematic view of the expandable dielectric
in the uterine wall perforation illustrating the escape of CO2 gas
and test failure mode.

[0052] FIG. 24 is a chart illustrating a combination two-stage cavity
integrity test wherein the first stage comprises the test described in
FIGS. 15-16 and the second stage comprises the test described in FIGS.
22A-23.

DETAILED DESCRIPTION

[0053] In the following description, various embodiments of the present
invention will be described. For purposes of explanation, specific
configurations and details are set forth in order to provide a thorough
understanding of the embodiments. However, it will also be apparent to
one skilled in the art that the present invention may be practiced
without the specific details. Furthermore, well-known features may be
omitted or simplified in order not to obscure the embodiment being
described.

[0054] In general, an electrosurgical ablation system is described herein
that comprises an elongated introducer member for accessing a patient's
uterine cavity with a working end that deploys an expandable thin-wall
dielectric structure containing an electrically non-conductive gas as a
dielectric. In one embodiment, an interior chamber of the thin-wall
dielectric structure contains a circulating neutral gas such as argon. An
RF power source provides current that is coupled to the neutral gas flow
by a first polarity electrode disposed within the interior chamber and a
second polarity electrode at an exterior of the working end. The gas
flow, which is converted to a conductive plasma by an electrode
arrangement, functions as a switching mechanism that permits current flow
to engaged endometrial tissue only when the voltage across the
combination of the gas, the thin-wall dielectric structure and the
engaged tissue reaches a threshold that causes capacitive coupling across
the thin-wall dielectric material. By capacitively coupling current to
tissue in this manner, the system provides a substantially uniform tissue
effect within all tissue in contact with the expanded dielectric
structure. Further, the invention allows the neutral gas to be created
contemporaneously with the capacitive coupling of current to tissue.

[0055] In general, this disclosure may use the terms "plasma", "conductive
gas" and "ionized gas" interchangeably. A plasma consists of a state of
matter in which electrons in a neutral gas are stripped or "ionized" from
their molecules or atoms. Such plasmas can be formed by application of an
electric field or by high temperatures. In a neutral gas, electrical
conductivity is non-existent or very low. Neutral gases act as a
dielectric or insulator until the electric field reaches a breakdown
value, freeing the electrons from the atoms in an avalanche process thus
forming a plasma. Such a plasma provides mobile electrons and positive
ions, and acts as a conductor which supports electric currents and can
form spark or arc. Due to their lower mass, the electrons in a plasma
accelerate more quickly in response to an electric field than the heavier
positive ions, and hence carry the bulk of the current.

[0056]FIG. 1 depicts one embodiment of an electrosurgical ablation system
100 configured for endometrial ablation. The system 100 includes a
hand-held apparatus 105 with a proximal handle 106 shaped for grasping
with a human hand that is coupled to an elongated introducer sleeve 110
having axis 111 that extends to a distal end 112. The introducer sleeve
110 can be fabricated of a thin-wall plastic, composite, ceramic or metal
in a round or oval cross-section having a diameter or major axis ranging
from about 4 mm to 8 mm in at least a distal portion of the sleeve that
accesses the uterine cavity. The handle 106 is fabricated of an
electrically insulative material such as a molded plastic with a
pistol-grip having first and second portions, 114a and 114b, that can be
squeezed toward one another to translate an elongated translatable sleeve
115 which is housed in a bore 120 in the elongated introducer sleeve 110.
By actuating the first and second handle portions, 114a and 114b, a
working end 122 can be deployed from a first retracted position (FIG. 1)
in the distal portion of bore 120 in introducer sleeve 110 to an extended
position as shown in FIG. 2. In FIG. 2, it can be seen that the first and
second handle portions, 114a and 114b, are in a second actuated position
with the working end 122 deployed from the bore 120 in introducer sleeve
110.

[0057] FIGS. 2 and 3 shows that ablation system 100 includes an RF energy
source 130A and RF controller 130B in a control unit 135. The RF energy
source 130A is connected to the hand-held device 105 by a flexible
conduit 136 with a plug-in connector 137 configured with a gas inflow
channel, a gas outflow channel, and first and second electrical leads for
connecting to receiving connector 138 in the control unit 135. The
control unit 135, as will be described further below in FIGS. 3 and 4,
further comprises a neutral gas inflow source 140A, gas flow controller
140B and optional vacuum or negative pressure source 145 to provide
controlled gas inflows and gas outflows to and from the working end 122.
The control unit 135 further includes a balloon inflation source 148 for
inflating an expandable sealing balloon 225 carried on introducer sleeve
110 as described further below.

[0058] Referring to FIG. 2, the working end 122 includes a flexible,
thin-wall member or structure 150 of a dielectric material that when
expanded has a triangular shape configured for contacting the patient's
endometrial lining that is targeted for ablation. In one embodiment as
shown in FIGS. 2, 5 and 6, the dielectric structure 150 comprises a
thin-wall material such as silicone with a fluid-tight interior chamber
152.

[0059] In an embodiment, an expandable-collapsible frame assembly 155 is
disposed in the interior chamber. Alternatively, the dielectric structure
may be expanded by a neutral gas without a frame, but using a frame
offers a number of advantages. First, the uterine cavity is flattened
with the opposing walls in contact with one another. Expanding a
balloon-type member may cause undesirable pain or spasms. For this
reason, a flat structure that is expanded by a frame is better suited for
deployment in the uterine cavity. Second, in embodiments herein, the
neutral gas is converted to a conductive plasma at a very low pressure
controlled by gas inflows and gas outflows--so that any pressurization of
a balloon-type member with the neutral gas may exceed a desired pressure
range and would require complex controls of gas inflows and gas outflows.
Third, as described below, the frame provides an electrode for contact
with the neutral gas in the interior chamber 152 of the dielectric
structure 150, and the frame 155 extends into all regions of the interior
chamber to insure electrode exposure to all regions of the neutral gas
and plasma. The frame 155 can be constructed of any flexible material
with at least portions of the frame functioning as spring elements to
move the thin-wall structure 150 from a collapsed configuration (FIG. 1)
to an expanded, deployed configuration (FIG. 2) in a patient's uterine
cavity. In one embodiment, the frame 155 comprises stainless steel
elements 158a, 158b and 160a and 160b that function akin to leaf springs.
The frame can be a stainless steel such as 316 SS, 17A SS, 420 SS, 440 SS
or the frame can be a NiTi material. The frame preferably extends along a
single plane, yet remains thin transverse to the plane, so that the frame
may expand into the uterine cavity. The frame elements can have a
thickness ranging from about 0.005'' to 0.025''. As can be seen in FIGS.
5 and 6, the proximal ends 162a and 162b of spring elements 158a, 158b
are fixed (e.g., by welds 164) to the distal end 165 of sleeve member
115. The proximal ends 166a and 166b of spring elements 160a, 160b are
welded to distal portion 168 of a secondary translatable sleeve 170 that
can be extended from bore 175 in translatable sleeve 115. The secondary
translatable sleeve 170 is dimensioned for a loose fit in bore 175 to
allow gas flows within bore 175. FIGS. 5 and 6 further illustrate the
distal ends 176a and 176b of spring elements 158a, 158b are welded to
distal ends 178a and 178b of spring elements 160a and 160b to thus
provide a frame 155 that can be moved from a linear shape (see FIG. 1) to
an expanded triangular shape (FIGS. 5 and 6).

[0060] As will be described further below, the bore 175 in sleeve 115 and
bore 180 in secondary translatable sleeve 170 function as gas outflow and
gas inflow lumens, respectively. It should be appreciated that the gas
inflow lumen can comprise any single lumen or plurality of lumens in
either sleeve 115 or sleeve 170 or another sleeve, or other parts of the
frame 155 or the at least one gas flow lumen can be formed into a wall of
dielectric structure 150. In FIGS. 5, 6 and 7 it can be seen that gas
inflows are provided through bore 180 in sleeve 170, and gas outflows are
provided in bore 175 of sleeve 115. However, the inflows and outflows can
be also be reversed between bores 175 and 180 of the various sleeves.
FIGS. 5 and 6 further show that a rounded bumper element 185 is provided
at the distal end of sleeve 170 to insure that no sharp edges of the
distal end of sleeve 170 can contact the inside of the thin dielectric
wall 150. In one embodiment, the bumper element 185 is silicone, but it
could also comprise a rounded metal element. FIGS. 5 and 6 also show that
a plurality of gas inflow ports 188 can be provided along a length of in
sleeve 170 in chamber 152, as well as a port 190 in the distal end of
sleeve 170 and bumper element 185. The sectional view of FIG. 7 also
shows the gas flow passageways within the interior of introducer sleeve
110.

[0061] It can be understood from FIGS. 1, 2, 5 and 6 that actuation of
first and second handle portions, 114a and 114b, (i) initially causes
movement of the assembly of sleeves 115 and 170 relative to bore 120 of
introducer sleeve 110, and (ii) secondarily causes extension of sleeve
170 from bore 175 in sleeve 115 to expand the frame 155 into the
triangular shape of FIG. 5. The dimensions of the triangular shape are
suited for a patient uterine cavity, and for example can have an axial
length A ranging from 4 to 10 cm and a maximum width B at the distal end
ranging from about 2 to 5 cm. In one embodiment, the thickness C of the
thin-wall structure 150 can be from 1 to 4 mm as determined by the
dimensions of spring elements 158a, 158b, 160a and 160b of frame assembly
155. It should be appreciated that the frame assembly 155 can comprise
round wire elements, flat spring elements, of any suitable metal or
polymer that can provide opening forces to move thin-wall structure 150
from a collapsed configuration to an expanded configuration within the
patient uterus. Alternatively, some elements of the frame 155 can be
spring elements and some elements can be flexible without inherent spring
characteristics.

[0062] As will be described below, the working end embodiment of FIGS. 2,
5 and 6 has a thin-wall structure 150 that is formed of a dielectric
material such as silicone that permits capacitive coupling of current to
engaged tissue while the frame assembly 155 provides structural support
to position the thin-wall structure 150 against tissue. Further, gas
inflows into the interior chamber 152 of the thin-wall structure can
assist in supporting the dielectric wall so as to contact endometrial
tissue. The dielectric thin-wall structure 150 can be free from fixation
to the frame assembly 155, or can be bonded to an outward-facing portion
or portions of frame elements 158a and 158b. The proximal end 182 of
thin-wall structure 150 is bonded to the exterior of the distal end of
sleeve 115 to thus provide a sealed, fluid-tight interior chamber 152
(FIG. 5).

[0063] In one embodiment, the gas inflow source 140A comprises one or more
compressed gas cartridges that communicate with flexible conduit 136
through plug-in connector 137 and receiving connector 138 in the control
unit 135 (FIGS. 1-2). As can be seen in FIGS. 5-6, the gas inflows from
source 140A flow through bore 180 in sleeve 170 to open terminations 188
and 190 therein to flow into interior chamber 152. A vacuum source 145 is
connected through conduit 136 and connector 137 to allow circulation of
gas flow through the interior chamber 152 of the thin-wall dielectric
structure 150. In FIGS. 5 and 6, it can be seen that gas outflows
communicate with vacuum source 145 through open end 200 of bore 175 in
sleeve 115. Referring to FIG. 5, it can be seen that frame elements 158a
and 158b are configured with a plurality of apertures 202 to allow for
gas flows through all interior portions of the frame elements, and thus
gas inflows from open terminations 188, 190 in bore 180 are free to
circulated through interior chamber 152 to return to an outflow path
through open end 200 of bore 175 of sleeve 115. As will be described
below (see FIGS. 3-4), the gas inflow source 140A is connected to a gas
flow or circulation controller 140B which controls a pressure regulator
205 and also controls vacuum source 145 which is adapted for assisting in
circulation of the gas. It should be appreciated that the frame elements
can be configured with apertures, notched edges or any other
configurations that allow for effective circulation of a gas through
interior chamber 152 of the thin-wall structure 150 between the inflow
and outflow passageways.

[0064] Now turning to the electrosurgical aspects of the invention, FIGS.
5 and 6 illustrate opposing polarity electrodes of the system 100 that
are configured to convert a flow of neutral gas in chamber 152 into a
plasma 208 (FIG. 6) and to allow capacitive coupling of current through a
wall 210 of the thin-wall dielectric structure 150 to endometrial tissue
in contact with the wall 210. The electrosurgical methods of capacitively
coupling RF current across a plasma 208 and dielectric wall 210 are
described in U.S. patent application Ser. No. 12/541,043; filed Aug. 13,
2009 (Atty. Docket No. 027980-000110US) and U.S. application Ser. No.
12/541,050 (Atty. Docket No. 027980-000120US), referenced above. In FIGS.
5 and 6, the first polarity electrode 215 is within interior chamber 152
to contact the neutral gas flow and comprises the frame assembly 155 that
is fabricated of an electrically conductive stainless steel. In another
embodiment, the first polarity electrode can be any element disposed
within the interior chamber 152, or extendable into interior chamber 152.
The first polarity electrode 215 is electrically coupled to sleeves 115
and 170 which extends through the introducer sleeve 110 to handle 106 and
conduit 136 and is connected to a first pole of the RF source energy
source 130A and controller 130B. A second polarity electrode 220 is
external of the internal chamber 152 and in one embodiment the electrode
is spaced apart from wall 210 of the thin-wall dielectric structure 150.
In one embodiment as depicted in FIGS. 5 and 6, the second polarity
electrode 220 comprises a surface element of an expandable balloon member
225 carried by introducer sleeve 110. The second polarity electrode 220
is coupled by a lead (not shown) that extends through the introducer
sleeve 110 and conduit 136 to a second pole of the RF source 130A. It
should be appreciated that second polarity electrode 220 can be
positioned on sleeve 110 or can be attached to surface portions of the
expandable thin-wall dielectric structure 150, as will be described
below, to provide suitable contact with body tissue to allow the
electrosurgical ablation of the method of the invention. The second
polarity electrode 220 can comprise a thin conductive metallic film, thin
metal wires, a conductive flexible polymer or a polymeric positive
temperature coefficient material. In one embodiment depicted in FIGS. 5
and 6, the expandable member 225 comprises a thin-wall compliant balloon
having a length of about 1 cm to 6 cm that can be expanded to seal the
cervical canal. The balloon 225 can be inflated with a gas or liquid by
any inflation source 148, and can comprise a syringe mechanism controlled
manually or by control unit 135. The balloon inflation source 148 is in
fluid communication with an inflation lumen 228 in introducer sleeve 110
that extends to an inflation chamber of balloon 225 (see FIG. 7).

[0065] Referring back to FIG. 1, the control unit 135 can include a
display 230 and touch screen or other controls 232 for setting and
controlling operational parameters such as treatment time intervals,
treatment algorithms, gas flows, power levels and the like. Suitable
gases for use in the system include argon, other noble gases and mixtures
thereof. In one embodiment, a footswitch 235 is coupled to the control
unit 135 for actuating the system.

[0066] The box diagrams of FIGS. 3 and 4 schematically depict the system
100, subsystems and components that are configured for an endometrial
ablation system. In the box diagram of FIG. 3, it can be seen that RF
energy source 130A and circuitry is controlled by a controller 130B. The
system can include feedback control systems that include signals relating
to operating parameters of the plasma in interior chamber 152 of the
dielectric structure 150. For example, feedback signals can be provided
from at least one temperature sensor 240 in the interior chamber 152 of
the dielectric structure 150, from a pressure sensor within, or in
communication, with interior chamber 152, and/or from a gas flow rate
sensor in an inflow or outflow channel of the system. FIG. 4 is a
schematic block diagram of the flow control components relating to the
flow of gas media through the system 100 and hand-held device 105. It can
be seen that a pressurized gas source 140A is linked to a downstream
pressure regulator 205, an inflow proportional valve 246, flow meter 248
and normally closed solenoid valve 250. The valve 250 is actuated by the
system operator which then allows a flow of a neutral gas from gas source
140A to circulate through flexible conduit 136 and the device 105. The
gas outflow side of the system includes a normally open solenoid valve
260, outflow proportional valve 262 and flow meter 264 that communicate
with vacuum pump or source 145. The gas can be exhausted into the
environment or into a containment system. A temperature sensor 270 (e.g.,
thermocouple) is shown in FIG. 4 that is configured for monitoring the
temperature of outflow gases. FIG. 4 further depicts an optional
subsystem 275 which comprises a vacuum source 280 and solenoid valve 285
coupled to the controller 140B for suctioning steam from a uterine cavity
302 at an exterior of the dielectric structure 150 during a treatment
interval. As can be understood from FIG. 4, the flow passageway from the
uterine cavity 302 can be through bore 120 in sleeve 110 (see FIGS. 2, 6
and 7) or another lumen in a wall of sleeve 110 can be provided.

[0067] FIGS. 8A-8D schematically illustrate a method of the invention
wherein (i) the thin-wall dielectric structure 150 is deployed within a
patient uterus and (ii) RF current is applied to a contained neutral gas
volume in the interior chamber 152 to contemporaneously create a plasma
208 in the chamber and capacitively couple current through the thin
dielectric wall 210 to apply ablative energy to the endometrial lining to
accomplish global endometrial ablation.

[0068] More in particular, FIG. 8A illustrates a patient uterus 300 with
uterine cavity 302 surrounded by endometrium 306 and myometrium 310. The
external cervical os 312 is the opening of the cervix 314 into the vagina
316. The internal os or opening 320 is a region of the cervical canal
that opens to the uterine cavity 302. FIG. 8A depicts a first step of a
method of the invention wherein the physician has introduced a distal
portion of sleeve 110 into the uterine cavity 302. The physician gently
can advance the sleeve 110 until its distal tip contacts the fundus 324
of the uterus. Prior to insertion of the device, the physician can
optionally introduce a sounding instrument into the uterine cavity to
determine uterine dimensions, for example from the internal os 320 to
fundus 324.

[0069]FIG. 8B illustrates a subsequent step of a method of the invention
wherein the physician begins to actuate the first and second handle
portions, 114a and 114b, and the introducer sleeve 110 retracts in the
proximal direction to expose the collapsed frame 155 and thin-wall
structure 150 within the uterine cavity 302. The sleeve 110 can be
retracted to expose a selected axial length of thin-wall dielectric
structure 150, which can be determined by markings 330 on sleeve 115 (see
FIG. 1) which indicate the axial travel of sleeve 115 relative to sleeve
170 and thus directly related to the length of deployed thin-wall
structure 150. FIG. 2 depicts the handle portions 114a and 114b fully
approximated thus deploying the thin-wall structure to its maximum
length.

[0070] FIG. 8C illustrates several subsequent steps of a method of the
invention. FIG. 8C first depicts the physician continuing to actuate the
first and second handle portions, 114a and 114b, which further actuates
the frame 155 (see FIGS. 5-6) to expand the frame 155 and thin-wall
structure 150 to a deployed triangular shape to contact the patient's
endometrial lining 306. The physician can slightly rotate and move the
expanding dielectric structure 150 back and forth as the structure is
opened to insure it is opened to the desired extent. In performing this
step, the physician can actuate handle portions, 114a and 114b, a
selected degree which causes a select length of travel of sleeve 170
relative to sleeve 115 which in turn opens the frame 155 to a selected
degree. The selected actuation of sleeve 170 relative to sleeve 115 also
controls the length of dielectric structure deployed from sleeve 110 into
the uterine cavity. Thus, the thin-wall structure 150 can be deployed in
the uterine cavity with a selected length, and the spring force of the
elements of frame 155 will open the structure 150 to a selected
triangular shape to contact or engage the endometrium 306. In one
embodiment, the expandable thin-wall structure 150 is urged toward and
maintained in an open position by the spring force of elements of the
frame 155. In the embodiment depicted in FIGS. 1 and 2, the handle 106
includes a locking mechanism with finger-actuated sliders 332 on either
side of the handle that engage a grip-lock element against a notch in
housing 333 coupled to introducer sleeve 110 (FIG. 2) to lock sleeves 115
and 170 relative to introducer sleeve 110 to maintain the thin-wall
dielectric structure 150 in the selected open position.

[0071] FIG. 8C further illustrates the physician expanding the expandable
balloon structure 225 from inflation source 148 to thus provide an
elongated sealing member to seal the cervix 314 outward from the internal
os 320. Following deployment of the thin-wall structure 150 and balloon
225 in the cervix 314, the system 100 is ready for the application of RF
energy to ablate endometrial tissue 306. FIG. 8C next depicts the
actuation of the system 100, for example, by actuating footswitch 235,
which commences a flow of neutral gas from source 140A into the interior
chamber 152 of the thin-wall dielectric structure 150. Contemporaneous
with, or after a selected delay, the system's actuation delivers RF
energy to the electrode arrangement which includes first polarity
electrode 215 (+) of frame 155 and the second polarity electrode 220 (-)
which is carried on the surface of expandable balloon member 225. The
delivery of RF energy delivery will instantly convert the neutral gas in
interior chamber 152 into conductive plasma 208 which in turn results in
capacitive coupling of current through the dielectric wall 210 of the
thin-wall structure 150 resulting in ohmic heating of the engaged tissue.
FIG. 8C schematically illustrates the multiplicity of RF current paths
350 between the plasma 208 and the second polarity electrode 220 through
the dielectric wall 210. By this method, it has been found that ablation
depths of three mm to six mm or more can be accomplished very rapidly,
for example in 60 seconds to 120 seconds dependent upon the selected
voltage and other operating parameters. In operation, the voltage at
which the neutral gas inflow, such as argon, becomes conductive (i.e.,
converted in part into a plasma) is dependent upon a number of factors
controlled by the controllers 130B and 140B, including the pressure of
the neutral gas, the volume of interior chamber 152, the flow rate of the
gas through the chamber 152, the distance between electrode 210 and
interior surfaces of the dielectric wall 210, the dielectric constant of
the dielectric wall 210 and the selected voltage applied by the RF source
130, all of which can be optimized by experimentation. In one embodiment,
the gas flow rate can be in the range of 5 ml/sec to 50 ml/sec. The
dielectric wall 210 can comprise a silicone material having a thickness
ranging from a 0.005'' to 0.015 and having a relative permittivity in the
range of 3 to 4. The gas can be argon supplied in a pressurized cartridge
which is commercially available. Pressure in the interior chamber 152 of
dielectric structure 150 can be maintained between 14 psia and 15 psia
with zero or negative differential pressure between gas inflow source
140A and negative pressure or vacuum source 145. The controller is
configured to maintain the pressure in interior chamber in a range that
varies by less than 10% or less than 5% from a target pressure. The RF
power source 130A can have a frequency of 450 to 550 KHz, and electrical
power can be provided within the range of 600 Vrms to about 1200 Vrms and
about 0.2 Amps to 0.4 Amps and an effective power of 40 W to 100 W. In
one method, the control unit 135 can be programmed to delivery RF energy
for a preselected time interval, for example, between 60 seconds and 120
seconds. One aspect of a treatment method corresponding to the invention
consists of ablating endometrial tissue with RF energy to elevate
endometrial tissue to a temperature greater than 45 degrees Celsius for a
time interval sufficient to ablate tissue to a depth of at least 1 mm.
Another aspect of the method of endometrial ablation of consists of
applying radiofrequency energy to elevate endometrial tissue to a
temperature greater than 45 degrees Celsius without damaging the
myometrium.

[0072] FIG. 8D illustrates a final step of the method wherein the
physician deflates the expandable balloon member 225 and then extends
sleeve 110 distally by actuating the handles 114a and 114b to collapse
frame 155 and then retracting the assembly from the uterine cavity 302.
Alternatively, the deployed working end 122 as shown in FIG. 8C can be
withdrawn in the proximal direction from the uterine cavity wherein the
frame 155 and thin-wall structure 150 will collapse as it is pulled
through the cervix. FIG. 8D shows the completed ablation with the ablated
endometrial tissue indicated at 360.

[0073] In another embodiment, the system can include an electrode
arrangement in the handle 106 or within the gas inflow channel to
pre-ionize the neutral gas flow before it reaches the interior chamber
152. For example, the gas inflow channel can be configured with axially
or radially spaced apart opposing polarity electrodes configured to
ionize the gas inflow. Such electrodes would be connected in separate
circuitry to an RF source. The first and second electrodes 215 (+) and
220 (-) described above would operate as described above to provide the
current that is capacitively coupled to tissue through the walls of the
dielectric structure 150. In all other respects, the system and method
would function as described above.

[0074] Now turning to FIGS. 9 and 10, an alternate working end 122 with
thin-wall dielectric structure 150 is shown. In this embodiment, the
thin-wall dielectric structure 150 is similar to that of FIGS. 5 and 6
except that the second polarity electrode 220' that is exterior of the
internal chamber 152 is disposed on a surface portion 370 of the
thin-wall dielectric structure 150. In this embodiment, the second
polarity electrode 220' comprises a thin-film conductive material, such
as gold, that is bonded to the exterior of thin-wall material 210 along
two lateral sides 354 of dielectric structure 150. It should be
appreciated that the second polarity electrode can comprise one or more
conductive elements disposed on the exterior of wall material 210, and
can extend axially, or transversely to axis 111 and can be singular or
multiple elements. In one embodiment shown in more detail in FIG. 10, the
second polarity electrode 220' can be fixed on another lubricious layer
360, such as a polyimide film, for example KAPTON®. The polyimide
tape extends about the lateral sides 354 of the dielectric structure 150
and provides protection to the wall 210 when it is advanced from or
withdrawn into bore 120 in sleeve 110. In operation, the RF delivery
method using the embodiment of FIGS. 9 and 10 is the same as described
above, with RF current being capacitively coupled from the plasma 208
through the wall 210 and endometrial tissue to the second polarity
electrode 220' to cause the ablation.

[0075] FIG. 9 further shows an optional temperature sensor 390, such as a
thermocouple, carried at an exterior of the dielectric structure 150. In
one method of use, the control unit 135 can acquire temperature feedback
signals from at least one temperature sensor 390 to modulate or terminate
RF energy delivery, or to modulate gas flows within the system. In a
related method of the invention, the control unit 135 can acquire
temperature feedback signals from temperature sensor 240 in interior
chamber 152 (FIG. 6 to modulate or terminate RF energy delivery or to
modulate gas flows within the system.

[0076] In another embodiment of the invention, FIGS. 11-14 depict systems
and methods for evaluating the integrity of the uterine cavity which may
be perforated or otherwise damaged by the transcervical introduction of
probes and instruments into a uterine cavity. If the uterine wall is
perforated, it would be preferable to defer any ablation treatment until
the uterine wall is healed. A method of the invention comprises
introducing transcervically a probe into a patient's uterine cavity,
providing a flow of a fluid (e.g., CO2) through the probe into the
uterine cavity and monitoring the rate of the flow to characterize the
uterine cavity as perforated or non-perforated based on a change in the
flow rate. If the flow rate drops to zero or close to zero, this
indicates that the uterine cavity is intact and not perforated. If the
flow rate does not drop to zero or close to zero, this indicates that a
fluid flow is leaking through a perforation in the uterine cavity 302
into the uterine cavity or escaping around an occlusion balloon that
occludes the cervical canal.

[0077] In FIG. 11, it can be seen how a pressurized fluid source 405 and
controller 410 for controlling and monitoring flows is in fluid
communication with lumen 120 of introducer sleeve 110 (see FIG. 7). In
one embodiment, the fluid source can be a pressurized cartridge
containing CO2 or another biocompatible gas. In FIG. 12, it can be seen
that fluid source 405 communicates with a flexible conduit 412 that is
connected to a "pig-tail" tubing connector 414 extending outward from
handle 106 of the hand-held probe. A tubing in the interior of handle
component 114a provides a flow passageway 415 to the lumen 120 in the
introducer sleeve. In another embodiment, the fluid source 405 and
flexible conduit 408 can be integrated into conduit 136 of FIG. 1.

[0078] In FIG. 11, it can be seen that the flow of fluid is introduced
into the uterine cavity 302 after the balloon 225 in the cervical canal
has been inflated and after the working end and dielectric structure 150
has been expanded into its triangular shape to occupy the uterine cavity.
Thus, the CO2 gas flows around the exterior surfaces of expanded
dielectric structure 150 to fill the uterine cavity. Alternatively, the
flow of CO2 can be provided after the balloon 225 in the cervical canal
is inflated but before the dielectric structure 150 is expanded.

[0079]FIG. 13 is a block diagram that schematically depicts the
components of subsystem 420 that provides the flow of CO2 to and through
the hand-held probe 105. It can be seen that pressurized fluid source 405
communicates with a downstream pressure regulator 422, a proportional
valve 424, flow meter 440, normally closed solenoid valve 450 and one-way
valve 452. The valve 450 upon actuation by the system operator allows a
flow of CO2 gas from source 405 at a predetermined flow rate and pressure
through the subsystem and into the uterine cavity 302.

[0080] In one embodiment of the method of operation, the physician
actuates the system and electronically opens valve 450 which can provide
a CO2 flow through the system. The controller 410 monitors the flow meter
or sensor 440 over an interval that can range from 1 second to 60
seconds, or 5 second to 30 seconds to determine the change in the rate of
flow and/or a change in the rate of flow. In an embodiment, the flow
sensor comprises a Honeywell AWM5000 Series Mass Airflow Sensor, for
example Model AWM5101, that measure flows in units of mass flow. In one
embodiment, the initial flow rate is between 0.05 slpm (standard liters
per minute) and 2.0 slpm, or between 0.1 slpm and 0.2 slpm. The
controller 410 includes a microprocessor or programmable logic device
that provides a feedback signal from the flow sensors indicating either
(i) that the flow rate has dropped to zero or close to zero to thus
characterize the uterine cavity as non-perforated, or (ii) that the flow
rate has not dropped to a predetermined threshold level within a
predetermined time interval to thus characterize the uterine cavity as
perforated or that there is a failure in occlusion balloon 225 or its
deployment so that the cervical canal is not occluded. In one embodiment,
the threshold level is 0.05 slpm for characterizing the uterine cavity as
non-perforated. In this embodiment, the controller provides a signal
indicating a non-perforated uterine cavity if the flow drops below 0.05
slpm between the fifth second of the flow and the flow time-out, which
can be, for example, 30 seconds.

[0081] FIG. 14 depicts aspects of an algorithm used by controller 410 to
accomplish a uterine cavity integrity check, with the first step
comprising actuating a footswitch or hand switch. Upon actuation, a timer
is initialized for 1 to 5 seconds to determine that a fluid source 405 is
capable of providing a fluid flow, which can be checked by a pressure
sensor between the source 405 and pressure regulator 422. If no flow is
detected, an error signal is provided, such as a visual display signal on
the control unit 135 (FIG. 1).

[0082] As can be understood from FIG. 14, after the fluid source 405 is
checked, the controller opens the supply solenoid valve 450 and a timer
is initialized for a 1 to 5 second test interval to insure fluid flows
through the subsystem 420 of FIG. 13, with either or both a flow meter
440 or a pressure sensor. At the same time as valve 450 is opened, a
timer is initialized for cavity integrity test interval of 30 seconds.
The controller 410 monitors the flow meter 440 and provides a signal
characterizing the uterine cavity as non-perforated if, at any time after
the initial 5 second check interval and before the end of the timed-out
period (e.g., the 30 second time-out), the flow rate drops below a
threshold minimum rate, in one embodiment, to below 0.05 slpm. If the
interval times out after 30 seconds and the flow rate does not drop below
this threshold, then a signal is generated that characterizes that the
uterine cavity is perforated. This signal also can indicate a failure of
the occlusion balloon 225.

[0083] Referring to FIG. 14, in one embodiment, in response or otherwise
as a result of the signal that the uterine cavity is not perforated, the
controller 410 can automatically enable and activate the RF ablation
system described above to perform an ablation procedure. The controller
410 can provide a time interval from 1 to 15 seconds to allow CO2 gas to
vent from the uterine cavity 302 before activating RF energy delivery. In
another embodiment, the endometrial ablation system may include the
optional subsystem 275 for exhausting fluids or gas from the uterine
cavity during an ablation treatment (see FIG. 4 and accompanying text).
This subsystem 275 can be actuated to exhaust CO2 from the uterine cavity
302 which include opening solenoid valve 285 shown in FIG. 4.

[0084] The system can further include an override to repeat the cavity
integrity check, for example, after evaluation and re-deployment of the
occlusion balloon 225.

[0085] FIGS. 15 and 16 represent another system and method for
characterizing the uterine cavity as being non-perforated so as to safely
permit an ablation procedure. This system and method utilizes variations
in the algorithms that introduce a gas media fluid into the uterine
cavity and thereafter measure the changes in flow rates in the gas media.
The system again is configured to introduce a gas into the uterine cavity
after deployment and expansion of an ablation device in the cavity. If
the flow rate drops of the gas to approximately zero, this indicates that
the uterine cavity is intact and not perforated. In the event, the flow
rate of the gas does not drop, there is likely a gas flow escaping from
the uterine cavity 302 through a perforation in the uterine wall.

[0086] FIG. 15 schematically illustrates three different conditions that
may occur when operating the system, which indicate whether the system is
functioning properly, and whether the uterine wall is non-perforated or
perforated. In FIG. 15, the vertical axis indicates a gas flow rate
measure in slpm (standard liters per minute), and the horizontal axis
represents time in seconds. In one system variation, a gas source 405
such as a pressurized cartridge containing CO2 is controlled by a
controller 410, and the gas is introduced into the uterine cavity through
a passageway in the device introducer sleeve 110 as described above
(FIGS. 11-13). The controller 410 and flowmeter monitors flows from the
device into the uterine cavity (FIG. 13). The initial flow rate can be in
the range of 0.010 slpm to 0.20 slpm. In one aspect of the invention, a
minimum flow rate has been found to be important as a system diagnostic
check to insure gas flow is reaching the uterine cavity. Thus, FIG. 15
illustrates gas flow rate curve in a "condition 1" that may occur when
the system fails in delivering gas through the passageways of the system.
In one variation, the "condition 1" will be represented by a flow rate
over time wherein the flow rate does not achieve a minimum threshold flow
rate, which can be from 0.010 slpm to 0.050 slpm over a predetermined
time interval. In one variation, the minimum flow rate is 0.035 slpm. The
time interval can be from 1 second to 15 seconds. This "condition 1" as
in FIG. 15 could occur, for example, if the gas supply tubing within the
device were kinked or pinched which would then prevent gas flow through
the system and into the uterine cavity. In a related variation that
indicates system failure, a controller algorithm can calculate the volume
of gas delivered, and if the volume is less than a threshold volume, then
a system failure or fault can be determined. The gas volume V1 is
represented by the "area under the curve" in FIG. 15, which is a function
of flow rate and time.

[0087] FIG. 15 further illustrates a flow rate curve in a "condition 2"
which corresponds to an intact, non-perforated uterine cavity. As can be
understood from a practical perspective, a gas flow into an intact
uterine cavity at a set pressure from a low pressure source, for example
within a range of 0.025 psi to 1.0 psi, would provide an increasing flow
rate into the cavity until the cavity was filled with gas, and thereafter
the flow rate would diminish to a very low or zero flow rate. Such a
"condition 2" flow rate curve as in FIG. 15 further assumes that there is
an adequate sealing mechanism in the cervical canal. Thus, if controller
obtains flow rate data from the flowmeter indicating "condition 2", then
the patient's uterus is non-perforated and is suitable for an ablation.
In operation, the controller can look at various specific aspects and
parameters of the flow rate curve of "condition 2" in FIG. 15 to
determine that the uterine cavity integrity test has passed, wherein such
parameters can comprise any single parameter or a combination of the
following parameters: (i) the flow rate falling below a threshold rate,
for example between 0.010-0.10 slpm; (ii) a change in rate of flow; (iii)
a peak flow rate; (iii) the total gas volume V2 delivered; (iv) an
actual flow rate at a point in time compared to a peak flow rate; (v) a
derivative of flow rate at a point in time, and (vi) any of the preceding
parameters combined with a predetermined time interval. In one
embodiment, a constant pressure (0.85 psi) gas is introduced and a
minimum threshold flow is set at 0.035 slpm. A peak flow is calculated
after a time interval of 2 to 15 seconds, and thereafter it is determined
if the flow rate diminished by at least 10%, 20%, 30%, 40% or 50% over a
time interval of less than 30 seconds.

[0088] FIG. 15 next illustrates a flow rate curve in "condition 3" which
represents a gas flow when there is a perforated wall in a uterine
cavity, which would allow the gas to escape into the abdominal cavity. In
FIG. 15, a gas flow at a constant pressure is shown ramping up in flow
rate until it levels off and may decline but not the rate of decline to
may not go below a threshold value or may not decline a significant
amount relative to a peak flow rate. Such a flow rate curve over time
would indicate that the gas is leaking from the uterine cavity.

[0089] Now turning to FIG. 16, an algorithm diagram is shown that describe
one variation in a method of operating a uterine cavity integrity test
based on measuring gas flow rates over a selected time interval. At the
top of the diagram, the physician actuates the system in which a valve
450 is opened to provide a CO2 flow through the system (FIG. 14).
The controller 410 provides a flow at a pressure, for example 0.85 psi.
The actuation of the system also starts a timer wherein a first interval
is 30 seconds or less. Over this 30-second interval, the controller
records the peak flow rate which typically can occur within 2 to 10
seconds, then monitors the flow rate over the remainder of the 30 second
interval and determined whether the flow rate drops 20% or more from the
peak flow rate. Then, the controller additionally monitors whether the
flow rate falls below a threshold value, for example 0.035 slpm. If these
two conditions are met, the test indicates that there is no leakage of
gas media from the uterine cavity. If the flow rates does not drop 20%
from its peak with 30 seconds together with flow being below threshold
value, then the test fails indicating a leak of gas from the uterine
cavity. Thereafter, the diagram in FIG. 16, indicates one additional test
which consists of calculating the volume of gas delivered and comparing
the volume to the maximum volume within a kinked gas delivery line. If
the delivered gas volume is less than the capacity of the gas delivery
line, then the test fails and the signal on the controller can indicate
this type of test failure. If the delivered gas volume is greater than
the capacity of a gas delivery line, then the test passes. In one
variation of the controller algorithm can then automatically actuate the
delivery of RF energy in an ablation cycle. Alternatively, the controller
can provide a signal that the test has passed, and the physician can
manually actuate the RF ablation system.

[0090] FIG. 17 schematically illustrates another system and method for
characterizing integrity of the walls of a uterine cavity. As can be seen
in FIG. 17, an introducer sleeve 510 carrying an expandable working end
520 in deployed in the uterine cavity 302. The working end includes a
balloon-like member 522 with a fluid-tight interior chamber 524. In one
embodiment, the working end 510 is expanded laterally by frame elements
526a and 526b, which is similar to previously described embodiments. In
addition, a pressurized gas source 540 is actuated to provide an
inflation gas thru interior sleeve 542 and ports 544 therein that further
expands and opens the working end 520 transverse to opening forces
applied by frame elements 526a and 526b. The inflation gas can comprise
an argon gas that later is converted to a plasma as described previously.
The inflation gas can pressurize the working end to a selected pressure
ranging from 0.10 psi to 10 psi. In one variation, the pressure can be
0.50 psi.

[0091] As can be seen in FIG. 17, an expandable member 548 or balloon is
expanded to prevent any gas flow outwardly through the bore 550 in
introducer sleeve 510. Thereafter, a gas inflow system 410 similar to
that of FIG. 13 is utilized to flow a gas source, such as CO2 into
the uterine cavity 302 (FIG. 17). In FIG. 17, the gas inflow is indicated
by arrows 555 which can comprise an inflow at a predetermined pressure
through passageway 558 as described above, and in one variation can be
0.85 psi. The test for uterine cavity integrity then can monitor one or
more gas leakage parameters relating to the inflation gas in the interior
chamber 524 of the working end 520. For example, the flow into the
uterine cavity 302 will cause an outflow of gas from the interior chamber
524 through passageway 558 which can be measure by a flow meter, or the
volume of gas outflow can be measured or the change in gas pressure can
be measured. If there is no leak in the uterine cavity, the parameter of
the inflation can in the interior chamber 524 will reach an equilibrium
in relation to the CO2 inflow into the cavity. If the inflation gas
parameter does not reach an equilibrium, then the change in parameter
(flow, volume or pressure) will indicate a leakage of gas from the
uterine cavity through a perforation. In general, a method of
characterizing the integrity of a patient's uterus comprises positioning
a probe working end is a patient's uterine cavity, the working end
comprising an inflated resilient structure, introducing a flow of a gas
through the probe into a uterine cavity exterior about the exterior of
the working end, and measuring a gas flow, gas volume or gas pressure
parameter of the inflation media in the inflated resilient structure in
response to the gas flow into the uterine cavity.

[0092] FIGS. 18A-20B illustrates other methods of characterizing and/or
treating a patient's uterus, which include a multi-stage test for uterine
wall integrity which enhances safety. In general, a multi-stage test
corresponding to the invention comprises positioning a probe working end
in a patient's uterine cavity, introducing a first fluid into the
expandable working end, introducing a second fluid into the uterine
cavity exterior of the working end, and performing first and second
monitoring tests relating to parameters of the first and second fluids to
thereby characterize a uterine wall. Thereafter, the physician can
actuate an ablation mechanism carried by the working end upon
characterization of the uterine wall as intact or non-perforated. In one
embodiment, the step of actuating the ablation mechanism is automated by
a controller upon a signal from at least one sensor that uterine cavity
is intact.

[0093] FIGS. 18A and 18B illustrate in more detail a two-stage method for
testing the integrity of a uterine wall or uterine cavity. In FIG. 18A,
it can be seen that the elongate introducer sleeve 510 carrying an
expandable working end 520 is properly deployed in the uterine cavity
302. The working end again includes an expandable thin-wall resilient
member such as a dielectric member 522 with a fluid-tight interior
chamber 524. The cervical seal 604 is positioned in the cervical canal
with a cervical cuff 606 expanded and the dielectric structure 522 is
expanded as described previously. FIG. 18A further illustrates an inflow
of CO2 gas from source 420 into the uterine cavity 302 through
sleeve 510 about the exterior of the dielectric structure 522. Thus, the
first test stage illustrated in FIG. 18A consists of the cavity integrity
test described above in conjunction with FIGS. 15-16 wherein the CO2
inflow is monitored for a predetermined decay in the CO2 flow rate
to determine whether a perforation in the uterine cavity may exist.

[0094] Now turning to FIG. 18B, a second stage of the test is illustrated.
In the second stage, Argon gas from source 610 is controlled by the
controller 615 to provide a flow into the interior chamber 524 of the
dielectric structure 522. As can be understood in FIG. 18B, any
significant or slight expansion of the dielectric surface 612 (see arrows
in FIG. 18B) by the Argon inflation in the dielectric structure 522 will
impinge on CO2 flows about the exterior of the dielectric structure
522. Thus, the second stage of the cavity integrity test includes
monitoring the flow rate of the CO2 with a flowmeter 625 for changes
that are indicative of expansion of the dielectric structure wall which
impinges on the CO2 flow rate. In FIG. 18B, it can be understood
that when the dielectric structure 522 is fully expanded within the
uterine cavity, there remains very little space between the dielectric
wall and the uterine wall for CO2 to flow. In other words, any
expansion of the dielectric structure 522 will result in a significant
change in flow of the CO2. In some cases, the flow meter coupled to
the CO2 inflow lumen can detect CO2 outflow. In the event the
system is configured for a circulating flow of CO2 into and out of
the dielectric structure, a flowmeter 625 can detect a change in the flow
rate caused by the dielectric structure impinging on such a flow rate.
The second stage of the test illustrated FIG. 18B this can confirm
dielectric structure 522 is properly deployed and expanded cavity 302.

[0095] FIG. 19 is a box diagram that indicates one [embodiment] mentioned
and the steps involved in the second stage of the two-stage cavity
integrity test. In one embodiment, CO2 flow to the exterior of the
dielectric structure is activated at T=zero. At T=2 seconds, the
controller 615 activates the Argon positive pressure source at a flow
rate of 0.8 SLPM using a flow control loop. Pressure for the Argon in the
interior chamber the dielectric structure can be set at 0.5 psig using
the proportional valve in the return line and a pressure sensing
mechanism. Thereafter, the controller monitors CO2 flows to
determine whether the Argon flow into the interior dielectric structure
impinges on CO2 flows. In one example, after 2 seconds, a
significant change the CO2 flows will indicate that the dielectric
structure is substantially positioned in the uterine cavity 302 and is
properly expanded. In this stage of the test, if the controller 615 does
not receive a signal indicating a change in CO2 flows, this
indicates that the dielectric structure 522 it is not deployed
substantially within the uterine cavity 302 and the working end may have
penetrated the wall of the uterine cavity to some extent and further is
plugging the perforation thus preventing any leak.

[0096] FIGS. 20A and 20B illustrate the two-stage cavity integrity test in
a situation wherein the dielectric structure 522 has at least partially
perforated the uterine wall, unlike the proper working end deployment as
depicted in FIGS. 18A-18B. As can be seen in FIG. 20A, the dielectric
structure 522 has penetrated the fundus 618 and is only partially opened.
Such a uterine wall perforation could occur in the fundus 618 or
elsewhere in the uterine wall in an asymmetrically shaped uterine cavity.
Such a perforation could be caused by the working end of the probe
itself, or the perforation could be caused by a sounding instrument that
is used in a preliminary step in which the physician measures the length
of the uterine cavity.

[0097] FIG. 20A illustrates the first stage of the two-part test wherein
CO2 flows from the CO2 source 620 into the uterine cavity 302
through the introducer sleeve 510 and about the exterior of the
dielectric structure 522. It can be seen that the gas flows may not
penetrate the perforation since the perforation may be effectively
plugged by the silicone surface of the dielectric structure 522. Thus,
FIG. 20A illustrates a condition wherein the first stage of the test
which monitors only CO2 flow would indicate that the cavity has no
perforations, when in fact there is a perforation that is masked by the
dielectric structure 522 plugging the perforation.

[0098] FIG. 20B illustrates the second stage of the two-stage test wherein
Argon is introduced into the interior chamber 524 the dielectric
structure 522. In FIG. 20B, it can be seen that the expansion of the
dielectric wall is limited as indicated by the arrows since the distal
portion 632 portion of the dielectric structure 522 is embedded and not
expandable within the perforation in the uterine fundus. In this case,
the introduction of Argon gas into the dielectric structure detects the
perforation in the uterine wall which otherwise would not have been
detected by the first stage of the test. In the situation indicated in
FIG. 20B, the flow of Argon would be constrained and there would be
little fluctuation in the CO2 flow rate--thus indicating that the
dielectric structure 522 is not properly expanded and likely is disposed
within a perforated uterine wall.

[0099]FIG. 21 illustrates another variation in the second stage of the
two-stage cavity integrity test that records and compares alternative
parameters of fluid flows within the uterine cavity 302 and in the
interior chamber 524 of dielectric structure 522. This method variation
compares a change in a gas pressure parameter in Argon gas in the
dielectric structure 522 over a time interval of several seconds. First,
the controller 615 turns on the Argon gas for 2 seconds at a flow rate of
0.8 SLPM using a flow control loop. The controller further sets the
dielectric pressure at 0.5 psig. Next, the controller turns on the
CO2 flow to the uterine cavity exterior of the dielectric structure.
The controller 615 is configured to insure that the CO2 flow is
sufficiently low to maintain a seal between the cervical cuff 606 and the
interior os of the cervical canal. If CO2 flow were higher than a
predetermined limit, the uterine integrity test could fail because of
CO2 leakage around the cervical cuff.

[0100] Next, the controller 615 turns off the Argon flow by closing a
valve in the Argon flow system. Thus, the dielectric is maintained at 0.5
psig. After 2 seconds, the Argon pressure (P1) is recorded with
CO2 flowing about the exterior of the dielectric. Next, the CO2
flow is turned off and the Argon pressure is recorded after one second,
which is Argon pressure P2 with no CO2 flowing about the
exterior of the dielectric. The final step then compares P1 and
P2. If P1 is greater than P2 (plus a predetermined margin)
the cavity integrity test is successful and characterizes the uterine
wall as non-perforated. If P1 is not greater than P2 (plus the
predetermined margin), the cavity integrity test is no successful and a
perforation detected message is displayed by the controller.

[0101] In general, a method corresponding to the invention for
characterizing a patient's uterus, comprises positioning an expandable
structure in a patient's uterine cavity, introducing a gas into the
uterine cavity exterior of expandable structure, introducing a gas into
the expandable structure, and monitoring a gas parameter in the gas both
interior and exterior of the expandable structure to thereby characterize
the uterine cavity as either perforated or non-perforated. The gas
introduced at the exterior of the expandable structure can be CO2.
The gas introduced into the interior of the expandable structure can be a
neutral gas. The method can monitor any gas parameter which is useful for
leak detection. In one variation, the leak detecting parameter is a gas
flow rate. In another variation, the leak detecting parameter is a gas
pressure. In another variation, the leak detecting parameter is gas
volume.

[0102] In general, the method can include monitoring the gas parameters
contemporaneously and/or sequentially. The monitoring step can monitor
gas parameters first in the uterine cavity and then subsequently in the
expandable structure, or vice versa. Further, the method can monitor a
gas parameter in the uterine cavity at least twice and can monitor a gas
parameter in the expandable structure at least twice.

[0103] Now turning to FIGS. 22A-22B, another variation of system and
method for operating a uterine cavity integrity test is based on
measuring a gas inflow rate into the uterine cavity. FIG. 22A depicts an
expandable working end or structure 700 that is operatively coupled to
subsystems described previously, i.e., a pressurized CO2 flow source
705 for providing gas inflow into the uterine cavity 302, a controller
710 for controlling gas inflows, and a flowmeter 715 operatively coupled
to the controller for measuring the rate of gas inflows. In this
embodiment, an additional negative pressure source 720 is provided for
applying negative pressure to an interior chamber 722 of the thin-wall
dielectric sheath 725 that again comprises a working end 700 similar to
embodiments described above. The working end of FIGS. 22A-22B again
includes an expandable frame 726 as in the FIGS. 5-6 that is expandable
within interior chamber 722 of thin-wall dielectric sheath 725. In FIG.
22A, the introducer sleeve 510 carrying the expandable working end 700 is
properly deployed in uterine cavity 302. The cervical seal 604 is
positioned in the cervical canal with a cervical cuff 606 expanded and
the dielectric sheath 725 is expanded as described previously. FIG. 22A
further illustrates an inflow of CO2 gas from source 705 into the
uterine cavity 302 through sleeve 510 about the exterior of the
dielectric structure or sheath 725.

[0104] The test depicted in FIG. 22A is similar to the cavity integrity
test described above in conjunction with FIGS. 15-16 wherein the CO2
inflow is monitored for a predetermined decay in the CO2 flow rate
to determine whether a perforation in the uterine cavity may exist. The
variation of the test in FIG. 22A adds an additional intermediate step.
Prior to initiating a CO2 inflow, the controller 715 and test
algorithm is configured to actuate negative pressure source 720 to
thereby suction gas from the interior chamber 722 of dielectric sheath
725 to suction the thin-wall sheath against the interior frame 726. The
negative pressure can be from 5 to 10 psi below ambient, or any similar
achievable negative pressure which is maintained for the subsequent step
of inflowing CO2 into the uterine cavity. FIG. 22A, the sheath
region 730 indicates walls that are suctioned and collapsed toward one
another separated only by the interior frame 726. As can be seen in FIG.
22A, the expandable dielectric sheath 725 and frame 726 is properly
expanded within the uterine cavity 302 and no perforations are shown. In
this case, referring back to FIGS. 15 and 16 and the accompanying text,
the cavity integrity test would provide an inflow of CO2 at an
initial or first flow rate of at least 0.040 slpm (if measured in free
air). The CO2 inflow would continue for up to 30 seconds or until
the flow rate decayed and remained below a second flow rate for a
selected time interval of at least 1 second, at least 2 seconds, 5 at
least seconds, or at least 10 seconds. In one system and method, the
second flow rate is less than the first flow rate and less than 0.050
slpm. In one method, the initial or first flow rate (in free air) is
0.070 slpm, the inflow is continued for 30 seconds or until the flow rate
decays to 0.034 slpm and then the flow rate continuously remains below
0.034 slpm for 5 seconds. If the previous conditions are met, then the
controller 710 would display a message and signal that the test indicates
that the uterine cavity is non-perforated. In one embodiment, the
controller 710 and operational algorithm is configured to automatically
activate the RF source to thereby initiate the endometrial ablation
treatment. In another embodiment, the controller 710 is configured only
to enable the RF source and thereafter the physician can manually
activate the RF source to initiate the ablation procedure.

[0105] The utility of the above-described cavity integrity test can be
understood with reference to FIG. 22B, which depicts the working end 700
and dielectric sheath 725 within an exemplary perforation 736 in the
uterine wall tissue 738. In FIG. 22B, it can be seen that the sheath 715
and interior frame 726 have a partially expanded configuration and
extending through a perforation that could have been created by a `sound`
instrument used to measure dimensions of the uterine cavity. FIG. 22B
depicts the controller 715 and algorithm after actuation of the cavity
integrity test wherein negative pressure source 720 is actuated to
suction gas from interior chamber 722 of dielectric sheath 725. In FIGS.
22B and 23, it can be seen that thin-wall dielectric sheath 725 is under
negative with sheath wall regions 730' suctioned and collapsed toward one
another and separated only by interior frame 726. FIG. 23 is an enlarged
cut-away view of the sheath 725 in the perforation of FIG. 22B and shows
best how the suctioned down sheath region 730' leaves a trough 740
between tissue 738 (hatched region) and the sheath 725 through which
inflowing CO2 can escape from the uterine cavity 302 through the
perforation 736 in tissue 738. Under the previous test parameters, the
CO2 flow would escape the uterine cavity 302 and the test algorithm
would find that there was no flow decay over a selected time interval
(e.g., 5 to 30 seconds). Thus, the controller 715 would display a message
that a perforation existed and the RF source would be disabled. In
contrast, if the sheath 725 was not under negative pressure, it can be
understood that the sheath 725 and interior frame 726 could plug the
perforation and thus prevent CO2 escape--which would then result in
flow decay which in turn would mask the perforation 736.

[0106] The cavity integrity test described above with reference to FIGS.
22A-22B can be used as a single stage test or it can be used sequentially
with the earlier described test of FIGS. 15-16. Such a two-stage test
could add an additional level of safety to cavity integrity testing.

[0107] FIG. 24 illustrates a two stage cavity integrity test wherein the
first stage is similar to that of FIGS. 15-16 and the second stage is the
test described with reference to FIGS. 22A-22B. More in particular, gas
inflow into the interior chamber 722 of the dielectric 725 is provided
until the pressure reaches a predetermined level which in one algorithm
is 0.50 psi. Thereafter, CO2 inflows into the uterine cavity are
initiated as described above and then flow decay is monitored until flow
diminished to less that a predetermined level which in on algorithm is
0.034 slpm. If this first aspect of the test is achieved in less that 10
seconds, 30 seconds or 60 seconds, then the second stage of the test is
as described with reference to FIGS. 22A-23 wherein the interior chamber
722 of the dielectric 725 is suctioned down against frame 726 and the
flow decay test is repeated over another predetermined time interval
which can be from 10 to 60 seconds. In all other respects, the two-stages
test depicted in FIG. 24 corresponds to the stages described individually
above.

[0108] Although particular embodiments of the present invention have been
described above in detail, it will be understood that this description is
merely for purposes of illustration and the above description of the
invention is not exhaustive. Specific features of the invention are shown
in some drawings and not in others, and this is for convenience only and
any feature may be combined with another in accordance with the
invention. A number of variations and alternatives will be apparent to
one having ordinary skills in the art. Such alternatives and variations
are intended to be included within the scope of the claims. Particular
features that are presented in dependent claims can be combined and fall
within the scope of the invention. The invention also encompasses
embodiments as if dependent claims were alternatively written in a
multiple dependent claim format with reference to other independent
claims.

[0109] Other variations are within the spirit of the present invention.
Thus, while the invention is susceptible to various modifications and
alternative constructions, certain illustrated embodiments thereof are
shown in the drawings and have been described above in detail. It should
be understood, however, that there is no intention to limit the invention
to the specific form or forms disclosed, but on the contrary, the
intention is to cover all modifications, alternative constructions, and
equivalents falling within the spirit and scope of the invention, as
defined in the appended claims.

[0110] The use of the terms "a" and "an" and "the" and similar referents
in the context of describing the invention (especially in the context of
the following claims) are to be construed to cover both the singular and
the plural, unless otherwise indicated herein or clearly contradicted by
context. The terms "comprising," "having," "including," and "containing"
are to be construed as open-ended terms (i.e., meaning "including, but
not limited to,") unless otherwise noted. The term "connected" is to be
construed as partly or wholly contained within, attached to, or joined
together, even if there is something intervening. Recitation of ranges of
values herein are merely intended to serve as a shorthand method of
referring individually to each separate value falling within the range,
unless otherwise indicated herein, and each separate value is
incorporated into the specification as if it were individually recited
herein. All methods described herein can be performed in any suitable
order unless otherwise indicated herein or otherwise clearly contradicted
by context. The use of any and all examples, or exemplary language (e.g.,
"such as") provided herein, is intended merely to better illuminate
embodiments of the invention and does not pose a limitation on the scope
of the invention unless otherwise claimed. No language in the
specification should be construed as indicating any non-claimed element
as essential to the practice of the invention.

[0111] Preferred embodiments of this invention are described herein,
including the best mode known to the inventors for carrying out the
invention. Variations of those preferred embodiments may become apparent
to those of ordinary skill in the art upon reading the foregoing
description. The inventors expect skilled artisans to employ such
variations as appropriate, and the inventors intend for the invention to
be practiced otherwise than as specifically described herein.
Accordingly, this invention includes all modifications and equivalents of
the subject matter recited in the claims appended hereto as permitted by
applicable law. Moreover, any combination of the above-described elements
in all possible variations thereof is encompassed by the invention unless
otherwise indicated herein or otherwise clearly contradicted by context.

[0112] All references, including publications, patent applications, and
patents, cited herein are hereby incorporated by reference to the same
extent as if each reference were individually and specifically indicated
to be incorporated by reference and were set forth in its entirety
herein.

Patent applications by Akos Toth, Tata HU

Patent applications by Csaba Truckai, Saratoga, CA US

Patent applications by Dominique Filloux, Redwood City, CA US

Patent applications by Robin Bek, Campbell, CA US

Patent applications by Tejas N. Mazmudar, Palo Alto, CA US

Patent applications by Minerva Surgical, Inc.

Patent applications in class Injecting gas into body canal or cavity

Patent applications in all subclasses Injecting gas into body canal or cavity